<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Document</title>
	<style>
		div {
			width: 0px;
			height: 0px;
			border-left: 100px solid #ff0000;
			border-right: 100px solid transparent;
			border-bottom: 100px solid #0000ff;
			border-top: 100px solid transparent;
		}
	</style>
</head>
<body>
	<div></div>
</body>
</html>